David and Barbara Mikkelson are among those trying to clean the cesspool. The unassuming California couple run Snopes, one of the most popular fact-checking destinations on the Web. After 14 years, they seem to have concluded that people are rather cavalier about the facts. “Rumors are a great source of comfort for people,” Mrs. Mikkelson said.

The enduring articles are the ones about everyday fears: computer viruses, scams, missing children. Some e-mail chain letters, like the one offering users $245 for forwarding the message, never fade away.

“People keep falling for the same kind of things over and over again,” Mr. Mikkelson said. Some readers always seem to think, for instance, that the government is trying to poison them: Mrs. Mikkelson said rumors about AIDS have been recycled into rumors about swine flu vaccines.

For the Mikkelsons, the site affirms what cultural critics have bemoaned for years: the rejection of nuance and facts that run contrary to one’s point of view. “Especially in politics, most everything has infinite shades of gray to it, but people just want things to be true or false,” Mr. Mikkelson said. “In the larger sense, it’s people wanting confirmation of their world view.”